Silicon carbide (SiC) is expected to be used as a material for a next-generation semiconductor device. SiC has better physical properties than silicon (Si). For example, the bandgap of SiC is three times more than that of Si, the breakdown field strength of SiC is about ten times more than that of Si, and the thermal conductivity of SiC is about three times more than that of Si. These characteristics are used to achieve a semiconductor device which has low loss and can operate at a high temperature.
However, when SiC is used to form a metal insulator semiconductor (MIS) structure, level density, such as interface state density, between a semiconductor and an insulating film is higher than that of Si. As a result, charge mobility is reduced and the on-resistance of a metal insulator semiconductor field effect transistor (MISFET) or an insulated gate bipolar transistor (IGBT) increases.